In 1860, Abraham Lincoln gave the speech about slavery at New York City's Cooper Union. It’s credited by some with winning him the presidency. Last night, politicians gathered there once again. This night couldn’t be compared with that occasion in importance or (certainly) in eloquence. But it had significance nonetheless.

This was the first time that all nine candidates for New York City mayor had agreed to appear at the same event. What brought them together was an Earth Day forum on sustainability hosted by the New York League of Conservation Voters and the Cooper Union Institute for Sustainable Design.

By the end of the evening, all the candidates except for one were pretty much elbowing each other aside to establish their sustainability credentials and their belief that making New York "greener" would result in economic as well as environmental benefits. In the post-Sandy environment of 2013, the candidates seemed unwilling to appear uninformed or wishy-washy about environmental issues. They confidently advanced a series of proposals that would have seemed overly ambitious or even silly just a few years back.

Former city councilmember Sal Albanese said he wants to aim for a "zero-waste future" by dramatically ramping up the city’s recycling program. City council speaker Christine Quinn, the front-runner, said that reducing the city’s carbon emission 80 percent by 2050 is "where we have to go," and said the city should use its massive purchasing power to affect the market for sustainably produced food.

Public advocate Bill DeBlasio called for aggressive financing structures to retrofit aging buildings to make them more energy-efficient. Former Bronx borough president Adolfo Carrión, running as an independent, said New York should be exploring vertical farming. Former Metropolitan Transportation Authority chairman Joe Lhota called for a multi-pronged, holistic approach to flood prevention that included restored wetlands and possibly oyster beds as well as harder infrastructure. Former comptroller Bill Thompson said "the next mayor of the city would be a fool to take steps back" from the current administration’s environmental agenda, known as PlaNYC.

Pushing beyond the goals of that sustainability blueprint, which was on the leading edge of urban policy when current mayor Michael Bloomberg announced it in 2007, was a theme for nearly every candidate. Which shows how far the city, and the country, have come in the intervening six years. Nationally, aggressive sustainability initiatives in cities such as Chicago and San Francisco have made New York nervous that it is falling behind. And behind is a place that New Yorkers don’t like to be.

The only candidate who allowed himself to appear less than thrilled about waving a green flag was billionaire grocer John Catsimatidis, who is running against Lhota for the Republican nomination. He was the sole candidate to express skepticism about man-made climate change, and he was also the only one who wouldn’t raise his hand in support of more bicycle commuting. Catsimatidis also downplayed the immediate potential for renewable energy, saying, "We can’t live in a fantasy world…. I like to live in the real world."

But by the end of the evening, it looked like Catsimatidis was the one out of touch with a new political reality in America’s biggest city.